The endoscope operation portion structure includes an operation portion main body 23 having a rectangular opening 24a and provided with a plurality of screw receiving portions 61 to 63, and an operation portion main body 23 inserted into the operation portion main body 23 from the opening portion 24a, And a frame member 40 having a plurality of fixing portions 41 to 43 fixed to the plurality of screw receiving portions 61 to 63 by the fixing member 51, and among the plurality of fixing portions 41 to 43, different side portions Two fixing portions 42, 43 are formed in a protruding direction orthogonal to the longitudinal direction from the longitudinal direction and the length L1 in the width direction orthogonal to the longitudinal direction of the frame member 40 at the position of the two fixing portions 42, L2 is longer than the length L4 in the long side direction of the opening 24a and shorter than the length L5 in the diagonal direction.内視鏡操作部構造は、矩形状の開口部24aを有し、複数のビス受部61~63が設けられた操作部本体23と、開口部24aから操作部本体23内に挿入されて、複数のビス受部61~63に固定部材51によって固定される複数の固定部41~43を有するフレーム部材40と、を備え、複数の固定部41~43のうち、フレーム部材40の異なる側部から長手方向に直交した離反する方向に2つの固定部42,43が突起形成されており、2つの固定部42,43の位置におけるフレーム部材40の長手方向に直交する幅方向の長さL1,L2が開口部24aの長辺方向の長さL4よりも長く、且つ対角方向の長さL5よりも短くした。
